Uncertainties in the decision-making process of megaprojects: the Zeebrugge new sea lock

Complexity and uncertainty are inherent to megaprojects. While the social cost−benefit analysis (SCBA) and environmental impact assessment (EIA) are increasingly used to support decision making (DM) in megaprojects, these instruments often ignore and avoid uncertainty communication, documentation and analysis. By using a conceptual uncertainty matrix for decision-support analyses, this paper questions how uncertainties are taken into account in the SCBA and EIA when making decisions. A document analysis is applied to the SCBA, EIA and other project documents from the research (planning) phase of an ongoing sea port megaproject in Zeebrugge, Flanders. The results show that uncertainties are barely documented nor analysed in the SCBA and EIA, but arise later during the DM process; mainly about which plan alternative is the best for achieving the project's objectives. Uncertainty or ambiguity about ‘the best alternative’ results from stakeholders’ different interpretations of the SCBA and EIA. The paper reveals that research about megaproject uncertainty and DM should not be limited to the boundaries of either an SCBA or EIA but to further extend the scope to look at the dynamic interplay between uncertainties like multiple decision-support instruments, stakeholders’ different interpretations of these instruments and perceptions about uncertainties, DM and the general process.